[compression_utils] Add script xzize

xzize is a tool to (re)compress to xz.

compression_utils/README

@@ -1,3 +1,5 @@
+# lz and uz #
+
 The lz script emulates and extends commands lz and uz from the mtools.
 
 It handles: tar, tar.gz, tar.bz2, tar.xz, tar.lzma and tar.Z (and
@@ -13,3 +15,17 @@ To install lz and uz, move put script in a directory in the PATH (for
 instance /usr/local/bin) and hard link it to uz:
   cp lz /usr/local/bin
   ln /usr/local/bin/{lz,uz}
+
+
+# xzize #
+
+The xzize script compresses an uncompressed file, or recompresses a
+compressed file to xz (with maximum compression level).
+
+Known compression formats are GZip (.gz), BZip2 (.bz2), LZMA (.lzma),
+and Lempel-Ziv (.Z).
+
+In case of recompression, the original compressed file is keeped. In
+case of compression (i.e. when the suffix of the file does not
+correspond to a known compression format), the original uncompressed
+file is removed.

compression_utils/xzize

@@ -0,0 +1,102 @@
+#!/bin/sh
+#
+# xzize, Copyright © 2010 Matteo Cypriani
+#
+# This program is free software. It comes without any warranty, to
+# the extent permitted by applicable law. You can redistribute it
+# and/or modify it under the terms of the Do What The Fuck You Want
+# To Public License, Version 2, as published by Sam Hocevar. See
+# http://sam.zoy.org/wtfpl/COPYING for more details.
+#
+# This script recompresses to xz (with maximum compression level) a
+# GZip (.gz), BZip2 (.bz2), LZMA (.lzma), and Lempel-Ziv (.Z)
+# compressed file. The original file is keeped.
+# If the file extension does not correspond to a known compression
+# format, the file is compressed to xz. In that case, the original
+# file is removed.
+
+
+set -u
+
+
+test_extension()
+{
+	local - FILE EXTENSION BASE
+	FILE="$1"
+	EXTENSION="$2"
+	BASE="`basename "$FILE" ."$EXTENSION"`"
+	if [ "$BASE" != "$FILE" ] ; then
+		DEST="$BASE".xz
+		return 0
+	fi
+	DEST="$FILE"
+	return 1
+}
+
+
+do_recompress()
+{
+	if [ -e "$DEST" ] ; then
+		echo "Skipping source file « $SOURCE »: destination file « $DEST » already exists!" >&2
+		return 0
+	fi
+	echo "Recompressing « $SOURCE » to  « $DEST »…"
+	$ACTION -c $SOURCE | xz -9 >$DEST
+	return $?
+}
+
+
+## Verify number of arguments ##
+
+if [ $# -lt 1 ] ; then
+	echo "$PROGRAM requires at least one argument!" >&2
+	exit 2
+fi
+
+
+## Process files ##
+
+for SOURCE in "$@" ; do
+
+	# GZip
+	test_extension "$SOURCE" gz
+	if [ "$DEST" != "$SOURCE" ] ; then
+		ACTION=gunzip
+		do_recompress
+		continue
+	fi
+
+	# BZip2
+	test_extension "$SOURCE" bz2
+	if [ "$DEST" != "$SOURCE" ] ; then
+		ACTION=bunzip2
+		do_recompress
+		continue
+	fi
+
+	# LZMA
+	test_extension "$SOURCE" lzma
+	if [ "$DEST" != "$SOURCE" ] ; then
+		ACTION=unlzma
+		do_recompress
+		continue
+	fi
+
+	# Compress
+	test_extension "$SOURCE" Z
+	if [ "$DEST" != "$SOURCE" ] ; then
+		ACTION=uncompress
+		do_recompress
+		continue
+	fi
+
+	# XZ
+	if test_extension "$SOURCE" xz ; then
+		echo "Skipping source file « $DEST »: it has already .xz suffix!" >&2
+		continue
+	fi
+
+	# Uncompressed file: fall back to simple compression
+	xz -9 "$SOURCE"
+
+done